Drill sharpener

ABSTRACT

A drill sharpener is provided which has a point-splitting port which simplifies the procedure for producing a split point on a drill bit undergoing sharpening. The point-splitting port is positioned relative to a grinding wheel assembly such that, when the drill held by a chuck is advanced toward the grinding wheel, a flute of the drill at the drill tip is brought into contact with the grinding wheel. The port has alignment stops therein which mate with flats provided on the barrel of the chuck to ensure proper alignment of the chuck and drill relative to the grinding wheel. The stops also limit the extent of inward travel of the chuck and drill to a predetermined distance. A debris or grit collection tube is also provided to be inserted into an unused port of the drill sharpener, to contain and confine any debris or grit attempting to exit the sharpener through the unused port.

CROSS-REFERENCE TO RELATED APPLICATION

This application relates to, and claims the benefit of the filing date,of U.S. Provisional Application Ser. No. 60/413,772, filed Sep. 27,2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a power drill sharpener, and morespecifically to a power drill sharpener having a push-in point splittingport and a tube designed to collect debris generated in a drillsharpening process.

2. Description of Related Art

Drill sharpeners are known for use in industrial environments. Inhigh-volume manufacturing operations, high-quality, precision drillsharpeners, even though quite expensive to purchase, are recognized asbeing cost effective devices. The use of a drill sharpener will prolongthe effective life of a drill, thereby reducing costs by reducingconsumption of the drill bits, and using sharp drill bits improvesproduction quality and yield of products requiring bores or holes to bedrilled therein during the production process. Further details relatingto the economics of employing a high quality drill sharpener can befound in U.S. Pat. No. 5,400,546, issued to Christian and Bernard.

The benefits of high quality drill sharpeners have also been appreciatedby smaller-volume operations, such as machine shops, other smallbusinesses, and by individual craftsmen and hobbyists who use drillsfrequently. The high cost of precision drill sharpeners historicallyrendered them less cost effective, due to the lower volume of drillingbeing performed. In addition, the industrial drill sharpeners are quitelarge, having a grinding wheel on the order of six (6) inches or more indiameter, with the overall unit having a footprint (area of a surfacetaken up by the unit resting thereon) of several square feet. Many smallbusinesses, and certainly hobbyists, would not normally have adequatespace to set up such a unit, even if it were somewhat cost effective.

Recently, advancements have been made, by one or more of the inventorsnamed herein, in the design of drill sharpeners, with the specificpurpose of reducing the size and manufacturing cost of the unit, whilemaintaining the precision at an acceptable level, and withoutsacrificing features related to setup and alignment which make thesharpeners easy to use and reliable. Those advancements have resulted inmaking high quality drill sharpeners available to a larger market thatincludes the lower volume operations, small businesses, craftsman andhobbyists. The less expensive, but still precise, sharpeners are alsoeven more cost effective, which further broadens the potential market.U.S. Pat. No. 5,735,732, which is hereby expressly incorporated byreference herein, discloses a drill sharpener configuration whichincorporates the advancements which yield a compact, less expensive,precise, and reliable drill sharpener suited for lower volume work.

SUMMARY OF THE INVENTION

The present invention relates to further enhancements or improvements ina compact drill sharpener which is generally of the type disclosed inU.S. Pat. No. 5,735,732 (“the '732 patent”). More specifically, thepresent invention is directed to a variant on the point-splitting portand method of splitting a point disclosed in the aforementioned patent.The point-splitting port of the present invention is believed to besimpler to use than that disclosed in the patent.

A further enhancement to the drill sharpener disclosed in the '732patent is provided in the present invention. The drill sharpener in apreferred embodiment has two ports into which a drill chuck holding adrill to be sharpened is inserted. One port is used to present the drillto the grinding wheel so that the faces and cutting edges of the drillcan be ground in the sharpening process. This will be referred to as asharpening port. A second port is the point-splitting port mentionedabove. This port is used to split the point of the drill (i.e., removethe web joining the inner portions of the two flutes) after the cuttingareas have been sharpened.

A considerable amount of debris is generated when the drill is beingsharpened, particularly in the sharpening of the cutting surfaces. Thedebris is primarily particles of the drill material that have beenground off, but also will include particles of the abrasive dislodgedfrom the grinding wheel, and possibly foreign materials that are presenton the surfaces being sharpened. The drill sharpener is provided with adebris collection chamber, which collects debris thrown from thegrinding wheel. However, in a preferred embodiment of this invention,the point-splitting port is located to the side of the unit, atapproximately the same level as the grinding wheel and the debriscollection chamber. As such, when the sharpening port is in use, thepoint-splitting port presents an opening near the grinding wheel wheredebris can exit the unit.

A debris collection tube has been developed which can be inserted intothe point-splitting port to substantially prevent debris from exitingthe unit. The tube is provided with a cap which will serve as a physicalbarrier to the debris, and is vented to allow airflow therethrough. Thecap is also removable if it is desired to attach the collection tube toa vacuum unit.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention and the attendantadvantages will be better understood from the ensuing DetailedDescription of the Preferred Embodiments, taken in conjunction with thedrawings filed herewith, in which:

FIG. 1 is a front elevation, partially cutaway, view of the drillsharpener according to a preferred embodiment of the present invention.

FIG. 2 is a perspective view of the drill sharpener and chuck accordingto an alternative preferred embodiment.

FIG. 3 is a further perspective view of a drill sharpener and chuck,with a portion of the housing removed, according to an alternativepreferred embodiment of the present invention.

FIG. 4 is a perspective view of the drill sharpener according to theFIG. 1 embodiment.

FIG. 5 is a top plan view, partially cutaway and partially incross-section, of the drill sharpener according to the FIG. 1embodiment.

FIG. 6 is a cross-sectional view of a grit collection tube according toa preferred embodiment of the present invention.

FIG. 7 is a side elevation view of the drill sharpener in accordancewith the FIG. 1 embodiment.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

The drill sharpener according to a preferred embodiment of the presentinvention includes a housing 10, which encloses a motor 12 and agrinding wheel assembly 14. The motor is preferably a high-speed motorcapable of operating at speeds on the order of about 15,000–20,000 RPM.The grinding wheel assembly is preferably substantially identical tothat disclosed in the '732 patent, and the diameter of thediamond-plated ring that forms the grinding surface is preferably on theorder of ½ to 2½ inches. Even more preferably, the diameter of the ringis about 1 to 1½ inches. Further, a diameter of 1¼ inches is preferred.

The grinding wheel assembly 14 is operably coupled to the shaft 16 ofthe motor, preferably in a direct drive engagement. It can be seen inthe several drawing figures that the unit may take on a verticalorientation, with the motor shaft extending vertically upwardly with thegrinding wheel assembly positioned above, in the manner disclosed in the'732 patent. Alternatively, the sharpener may be in a horizontalorientation, as seen in FIGS. 1, 4 and 5, in which the axis of the motorshaft extends along a substantially horizontal axis. The grinding wheelassembly is likewise oriented 90° from the other embodiment, and willrotate in a vertical “plane”.

Each of these alternative designs will have a sharpening port and apoint-splitting port. In addition, a drill bit alignment port 20, 20′ ispreferably provided so that the drill bit 200 can be properly positionedin a holder, namely a chuck 100, of the type described in the '732patent. The process for initially setting up the drill bit 200 to besharpened in the chuck is also as described in the '732 patent.

In sharpening a drill using this drill sharpening unit, the chuck 100holding the drill 200 in proper alignment therein is inserted into thesharpening port 30, 30′, and sharpened in the manner disclosed in the'732 patent. Thereafter, if it is desired to provide the drill with asplit point (either if the drill was initially a split point drill, orif it is desired to convert the drill being sharpened to a split pointdrill), the chuck and drill are then positioned to be inserted into thepoint-splitting port 40, 40′. In the '732 patent, the point splittingport was designed to receive the chuck fully therein without the drillcontacting the grinding wheel. That port was designed to permit the userto rock the chuck 100 and drill 200 back and forth, such that the propersurface of the drill point would be brought into contact with thegrinding wheel to remove material from the web of the drill, to therebysplit the point.

The point-splitting port of the present invention allows for muchsimpler operation. The port 40, 40′ is oriented relative to the ring ofthe grinding wheel assembly 14 such that, when the chuck 100 and drill200 are inserted into the port in proper alignment, the inner portion202 of the tip of the flute will contact the grinding ring and apredetermined amount of material will be ground off as the chuck anddrill are further advanced into the port. The port has stops 42positioned therein to limit the depth to which the chuck can beinserted. Those stops are configured and positioned to engage and tocooperate with two opposing flats 102 presented on a forward portion ofthe chuck 100.

The stops 42 present complementary engagement surfaces for the flats 102on the chuck, and initially, upon insertion of the chuck into the port,serve to orient the chuck in the proper position to present thenecessary surface of the drill to the grinding wheel assembly 14. Inother words, when the user begins to insert the chuck into the port, thestops 42 will prevent insertion at any orientation in which the flats102 are not matched up with the stops, by physically interfering withthe otherwise cylindrical surface of the chuck. The user must rotate thechuck until the flats and stops come into register. The chuck may thenbe pushed further into the port, to push the drill into contact with thegrinding wheel.

Upon further insertion of the chuck, the stops will engage thecylindrical barrel 104 of the chuck at the point where the flatsterminate. The stops thus will prevent further insertion of the chuck,signifying to the user that the grinding operation is complete. Thepoint splitting operation requires that the inner portion of both flutesof the drill 200 be ground, and thus, after completing the firstinsertion, the user retracts the chuck, rotates it 180°, and reinsertsthe chuck. The stops again permit the chuck to be inserted only when theflats 102 on the chuck are in register with the stops 42. The user thenpushes the chuck forward into the port to grind the other flute toproduce the completed split point. The port thus allows the point to besplit using a simple push-in motion.

The specific construction of the port, and the positioning thereofrelative to the grinding surface are significant factors in providingthe ability to split the point using just a pushing motion. As seenespecially in FIG. 7, the port is a generally circular and cylindricalopening in the housing with substantially cylindrical walls extendinginwardly toward the grinding wheel. The stops 42 preferably comprise twodiametrically opposed raised sections which protrude radially inwardlyfrom the cylindrical walls. The stops, as discussed previously, presenttwo parallel surfaces past which the flats on the chuck may slide. Thestops 42 are positioned, and the chuck flats 102 are sized, so as topermit the chuck to be inserted into the port to a predetermineddistance, at which distance, the drill carried by the chuck will haveengaged the grinding wheel along a desired portion thereof, on the orderof ⅛ of an inch. The grinding of the inner surface of the two flutes tosuch a distance will produce a split point. It can be seen in FIG. 7that the flutes will be directed into contact with an edge 26 of thegrinding wheel 24, which will control the amount of material removedfrom the drill flutes.

The point-splitting port has a preload element 44 which facilitates theprecise insertion of the chuck into the port at the same position andangle of orientation each time. The inwardly protruding cylindrical wallin the port has an open section along a portion of the wall. A tab 46 isprovided to extend into this open section, with the tongue of the tabbeing positioned substantially at the same circumferential position aswhere the wall would otherwise be located. At the free end of thetongue, the tab has a radially inwardly extending flange 48. This flangeprotrudes inwardly for a short distance into the opening defined by thecylindrical wall of the port 40. The flange engages the outer surface ofthe chuck barrel 104 when the chuck barrel is inserted, to position orcenter the chuck barrel in the port. The tongue has some degree offlexibility to prevent any binding of the chuck within the port.

The use of this preload element 44 enables the port opening to be sizedslightly larger overall than the size of the chuck barrel beingintroduced therein. Without the preload element, the size of the openingwould have to be nearly identical to the outer diameter of the chuckbarrel, in order to have the chuck enter at the same position each time.This would, however, greatly increase the cost of manufacture, in thatthe tolerances for the size of the opening would have to be muchsmaller. In addition, even using very tight tolerances, the chances ofthe chuck binding up in the port would be substantially higher. Thepreload element accomplishes the same result by contacting only a smallsection of the chuck barrel being inserted, and using that contact toproperly center the chuck within the port.

As can be seen in the unit illustrated in FIGS. 4, 5, and 7, which hasthe so-called horizontal orientation, the point-splitting port 40 islocated at the side of the unit. The debris-catching chamber 50 is atthe front of the unit, and will have a removable plastic cover 52, whichis preferably transparent or translucent, extending across and aroundthe exposed area shown in the drawing figure. It will be recognized thatthe point-splitting port 40 constitutes a fairly large opening throughwhich debris can escape while the sharpening port 30 is in use.

In order to substantially eliminate or minimize the amount of debrisexiting the unit while in operation, a debris collection tube 60,preferably of the configuration shown in FIG. 6, may be provided. Thedebris collection tube is shown in cross section, but it will readily berecognized that the tube will be cylindrical and of a size that willenable the tube to be inserted into the point-splitting port (as well asthe sharpening port, which is of essentially the same diameter). Thetube may preferably have one or more external ribs 62 which aid inseating the tube inside the port, and provide some measure of sealingthe tube against the cylindrical wall of the port 40.

As shown in this preferred embodiment, the tube is formed in the mannerof an elbow, and the portion protruding from the port can preferably becanted downwardly to collect particles with the aid of gravity as thedebris flows into and through the tube. A cap 64 is provided at theoutward extent of the tube, and spacing between the cap and the tube isprovided to allow for the venting of air while the cap operates to trapthe grit and other debris inside the tube.

The cap is preferably made to be removable, to allow it to be removedand to allow a vacuum hose, such as a Shop-Vac hose or tube, to beconnected thereto, to draw out the debris from the area of the grindingwheel. In a preferred embodiment, the outer end of the tube will besized and configured to mate with a 1¼ inch diameter Shop-Vac tube.

The foregoing description and appended drawings represent one or morepreferred embodiments of the invention. Various modifications andenhancements may become apparent to those of ordinary skill in the art,and such modifications and enhancements are within the spirit and scopeof the invention. The scope of the invention is defined by the appendedclaims.

1. A drill sharpener comprising a housing which encloses a rotatablegrinding wheel assembly, the housing having a point-splitting port tofacilitate a point-splitting operation upon a multi-flute drill bit toremove material between said flutes, the port comprising a guide featurethat maintains a longitudinal length of the bit along a predeterminedaxial line and at a predetermined angular orientation with respect tosaid line as said material is removed by the grinding wheel assembly,and wherein the point-splitting operation is carried out by insertingthe bit into the port and using the guide feature to maintain the bit ina first orientation while removing a first portion of said material fromthe bit, removing the bit from the port, and reinserting the bit intothe port and using the guide feature to maintain the bit in a secondorientation that is 180 degrees opposite the first orientation withrespect to the axial line while removing a second portion of saidmaterial from the bit, wherein said point-splitting port has an openingslightly larger than a barrel of a chuck to be inserted therein, thechuck adapted to hold said bit during said point-splitting operation,wherein the guide feature cooperates with a surface of the chuck tomaintain the bit along said predetermined axial line and a saidpredetermined angular orientation, and wherein the port furthercomprises a generally cylindrical wall of the housing and wherein theguide feature comprises a resilient portion of said generallycylindrical wall and a flange protruding radially inwardly from saidresilient portion of said wall.
 2. A drill sharpener as recited in claim1, wherein said resilient portion of said wall comprises a tongueelement formed in said wall and attached to said wall at one endthereof.
 3. A drill sharpener as recited in claim 1, wherein the portfurther comprises a stop feature that limits further advancement of thebit along the predetermined axial line to limit the amount of saidmaterial removed from said bit.
 4. A drill sharpener as recited in claim1, further comprising a chuck adapted to support the bit duringinsertion of the bit into the port, the chuck comprising an outersurface with a recess extending therein, the recess configured to engagethe guide feature of the port.
 5. A drill sharpener comprising a housingwhich encloses a grinding wheel assembly and a chuck adapted to securelyretain a multi-flute drill bit, the housing comprising a sharpening portadapted to receive the chuck to present said drill bit to the grindingwheel assembly to sharpen said flutes, the housing further comprising apoint-splitting port adapted to receive the chuck to present said drillbit to the grinding wheel assembly to remove material between saidflutes, wherein the point-splitting port comprises a guide feature thatmaintains a longitudinal length of the bit along a predetermined axialline and at a constant angular orientation with respect to said lineprior to and during the point-splitting operation, wherein thepoint-splitting port further comprises a generally cylindrical wall ofthe housing and wherein the guide feature comprises a resilient portionof said generally cylindrical wall and a flange protruding radiallyinwardly from said resilient portion of said wall.
 6. A drill sharpeneras recited in claim 5, wherein the point-splitting port has an openingslightly larger than a barrel of the chuck, and wherein the guidefeature cooperates with a surface of the chuck to maintain the bit alongsaid predetermined axial line and at said predetermined angularorientation during the point-splitting operation.
 7. A drill sharpeneras recited in claim 5, wherein said resilient portion comprises a tongueelement formed in said wall and attached to said wall at one endthereof.
 8. A drill sharpener as recited in claim 5, wherein thepoint-splitting port further comprises a stop feature that limitsfurther advancement of the bit along the predetermined axial line tolimit the amount of said material removed from said bit.
 9. A drillsharpener as recited in claim 5, wherein the housing further comprises asharpening port adapted to receive the chuck to present said drill bitto the grinding wheel assembly to sharpen said flutes, wherein the drillsharpener further comprises a debris collector to collect debris fromthe grinding wheel assembly, and wherein the collector is adapted to beremoveably coupled to either one of said ports while the chuck isinserted into the remaining one of said ports.